Improve src/Grammar/README.md file (installing PEGjs globally is no longer needed).
Improve BUILDING.md (installing PhantomJS separately is no longer needed).
Fix TURN settings syntax (use 'credential' instead of 'password').
Deleted remaining useless references to 'register_min_expires'
Fix turn_servers configuration parameter check
Enhancement #85. Enhance UA.contact.toString logic. Thanks @wakamoleguy
Fix #190. Allow defining an empty Stun Server Set. Thanks @dpocock
Fix #193. Do not reference extraHeaders parameter, but clone it instead

to avoid header duplication when apps use a global variable
Hold/Mute implementation
Add the sdp task to the default Grunt task
Use grunt-browserify instead of browserify
Update to sdp-transform 0.5.0 (fix #185 and fix #186).
Require sdp-transform 0.5.1 (may fix #46).
Require "sdp-transform": "~0.5.3" (fix missing fields in ICE candidate)
Add Content-Length:0 in ACK for [3456]XX responses (prevent issues with some SIP WS server implementations expecting Content-Length)
Merge branch 'hold' of github.com:versatica/JsSIP into hold

Conflicts:
	src/RTCSession.js